v0.2.27 — Codex delegation + chat API grounding gate

Two headline additions plus memory/observability polish. Early/experimental, macOS only.

Added

• Codex delegation (opt-in). With a ChatGPT Plus/Pro subscription + the official codex CLI installed and logged in, point Muse's chat/ask at it — Muse shells to the official CLI (read-only sandbox, ephemeral, neutral workdir) and never touches your OAuth token. OFF by default (local stays default), selected via --model codex/codex-default or an opt-in setup choice, blocked under MUSE_LOCAL_ONLY=true. Using a ChatGPT subscription to back a third-party app is an unofficial gray-area route (a cloud API key is the clean path) — Muse says so up front. Text answers only; Muse still grounds + cites the result.
• Compaction failure telemetry — memory-compaction failures classified into bounded reasons instead of opaque strings.
• muse browsing search --json emits the same grounded block as muse ask --json.

Fixed

• The chat API is now grounded like everything else. /chat, /api/chat and the streaming variants route through the same deterministic grounding + citation gate as /api/ask: an ungroundable claim is dropped by code (→ "I'm not sure"), a grounded answer passes unchanged, and the response carries the grounding verdict — closing a real hole in Muse's core "every claim cites a real source" guarantee.
• chat-ink grounding parity (Korean NFC input, pronoun-rewrite) now regression-guarded.